🧮 Java Socket Math Server

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📌 1. Project Description

This project implements a Client-Server architecture based on the TCP protocol. The Server accepts requests for mathematical operations from multiple clients simultaneously (Multithreaded) and logs all activity in a dedicated log file.

📂 2. File Structure

The project consists of the following core files:

• MathServer.java: The main Server class. It creates the ServerSocket on port 5555 and assigns each new connection to a separate thread.
• ClientHandler.java: The class that manages communication with each individual client. It implements the custom communication protocol, performs calculations, maintains user history, and handles file logging.
• MathClient.java: The client application. It connects to the Server, reads commands from the user, and displays the server's responses.
• server.log: An auto-generated file containing the history of all requests (Timestamp, IP Address, Command). (Note: This file should not be pushed to version control).

🛠 3. Compilation Instructions

To compile the code, open a terminal in the project directory and run the following command:

javac MathServer.java ClientHandler.java MathClient.java

🚀 4. Execution Instructions

The application requires at least two separate terminal windows: one for the Server and one (or more) for the Clients.

Step 1: Start the Server

In your first terminal, run:

java MathServer

(You will see a message confirming: "O Server ξεκίνησε στην θύρα 5555...")

Step 2: Start a Client

In a second terminal, run:

java MathClient

(You will see a connection success message and a prompt to enter commands).

⌨️ 5. Supported Commands

The user can input the following commands:

• ADD x y : Addition (e.g., ADD 10 5 -> Result: 15.0)
• SUB x y : Subtraction (e.g., SUB 10 2)
• MUL x y : Multiplication (e.g., MUL 5 5)
• DIV x y : Division (e.g., DIV 20 4)
• POW x y : Power / Exponentiation (e.g., POW 2 3 -> 2 to the power of 3)
• LAST : Displays the result of the last successful calculation.
• COUNT : Displays the total number of requests made by the current user.
• HIST : Displays a list of the user's last 5 commands (History).
• HELP : Shows the list of available commands.
• EXIT : Disconnects from the Server and terminates the client program.

🧠 6. Implementation Notes

• Multithreaded Architecture: The Server spawns a new thread for every client, allowing concurrent request handling without blocking.
• Thread-Safe Logging: Writing to the server.log file is synchronized to prevent race conditions when multiple threads attempt to log data simultaneously.
• Stateful Connections: The history and statistical data (COUNT, LAST, HIST) are maintained independently for each connected client in memory.